Harnisch et al., U.S. Pat. No. 4,919,848 discloses naphthalic acid imides useful as charge-regulating substances useful in electrophotographic toners.
Brana et al., U.S. Pat. No. 4,874,863 discloses anticancer compounds of the formula: ##STR1## wherein X.sup.1, X.sup.2, X.sup.3 and X.sup.4 are identical or different and are each H, NO.sub.2, NH.sub.2, C.sub.1 -C.sub.6 -alkylamino, di-C.sub.1 -C.sub.6 -alkylamino, OH, C.sub.1 -C.sub.6 -alkoxy, halogen, trihalomethyl, C.sub.1 -C.sub.6 alkyl, formyl, C.sub.1 -C.sub.6 -alkylcarbonyl, C.sub.1 -C.sub.6 -acylamino, ureyl, C.sub.1 -C.sub.6 -alkylureyl, or C.sub.1 -C.sub.6 -alkylcarbonylamino and R is a straight chain or branched C.sub.4 -C.sub.10 -alkylene which is interrupted at one or two points in the chain by a secondary or tertiary amino group, where 2 nitrogen atoms may additionally be bonded to one another by an alkylene group, or a salt with a physiologically tolerated acid.
Brana et al., U.S. Pat. No. 4,874,863 does not specifically disclose the compounds of the present invention. The compounds specifically disclosed in U.S. Pat. No. 4,874,863 are substantially less soluble than the compounds of the present invention and therefore present formulation problems when trying to formulate such compounds into a dosage form suitable for human use.
It has been found that the compounds of the present invention have dramatically increased water solubility which is an unexpected advantage over the compounds of the above identified patent.
In addition, the compounds of the present invention exhibit unexpected superior antitumor activity relative to the compounds specifically disclosed by Brana et al.